Improvement in compounds for hardening iron and steel



UNITED STATES PATENT OFFICE.

' JOHN MCDONALD, OF KANKAKEE, ILLINOIS.

Specification forming part of Letters Patent No. 121,645, dated December 5, 1871.

To all whom it may concern:

Be it known that I, JOHN MCDONALD, of Kankakee, in the county of Kankakee and State of Illinois, have invented certain Improvements in Chemical Compound for Hardening Iron and Steel; and I do hereby declare that the following is a full, clear, and exact description of the same.

This invention relates to a new and useful improvement in a liquid composition for hardening iron and steel, as farming implements, plows, cultivator-teeth, edge-tools, 850.; and it consists in the use of a compound formed of the ingredients hereinafter named, and applied as described.

In carrying out my invention and discovery I form a compound of the following articles, and in about the proportions named, viz.: ten gallons Whale or seal-oil; three and one-half pounds gum ara-bic; three and one-half pounds common salt; three and one-half pounds prussiate of potash; three pounds sulphate of zinc; and five pounds saltpeter.

The iron to be hardened-mold-boards, plowpoints, cultivator-teeth, &c.is smoothed off by grinding in the usual manner, and then heated to a temperature a little above a cherry-red color, and then immersed in the compound and allowed to remain until nearly cooled. Then the articles are removed and quickly plunged into cold brine--salt and Waterwhen they are ready for use. When the mold-boards or other articles of iron are treated in this manner they are not liable to spring, and are thoroughly hardened, so that their durability is greatly increased. Edge-tools and other articles of steel maybe hardened in a similar manner, but the process may be varied according to the temper required.

Having thus described my invention I claim as new and desire to secure by Letters Patent- The above compound, as and for the purposes described.

JOHN MCDONALD.

Witnesses:

J AMES H. PADDOCK, Gems. P. SWIGERT. 

